Push-type grates for coolers for cement clinker and suchlike pourable combustible material are known, these push-type grates being formed by grate-plate rows which extend transversely relative to the longitudinal direction of the grate and to the conveying direction of the material and which are alternately stationary and moved back and forth in the conveying direction. The individual grate plates of each row have a topside which forms the bearing surface for the bed of material to be cooled. They are carried by a grate-plate carrier, to which they are connected in the rear region of their underside via corresponding connection devices. They project forwards from the grate-plate carrier, in order to overlap the rear part of the grate plates of the next following grate-plate row. Under the load of the material resting on them, they are exposed to a bending moment and consequently, to support their front part, have stiffening devices which transmit the bending stress from the front plate part to the grate-plate carrier. The stiffening devices can be formed, for example, by longitudinal ribs (DE-C 24 32 599), by sidewalls of a box-shaped plate (EP-A 167,658; EP-A 337,383), by longitudinal battens of a frame-shaped design (EP-A 537,523) or by any other elements extending in the longitudinal direction. For the sake of simplicity, they are referred to here, in sum, as longitudinally extending ribs. These known grate plates are exposed on the topside to the high temperature of the material to be cooled and on the underside to the low temperature of the cooling air. They therefore expand to a greater extent on the topside than on the underside, this leading to arching or warping, as a result of which their front edge sinks a little. This may cause it to rub on the topside of the next following plate.
This also applies to box-shaped plates (EP-A 537,523, EP-A 337,383) which are composed of two plate parts arranged one above the other, namely of an upper frame-shaped part, the sidewalls of which form the said ribs, and a plate-shaped lower part. This disadvantage can be avoided by providing, by virtue of construction, appropriately large vertical play between successive plates, although this is undesirable because it causes more material to fall through in the region of overlap on the plates. There is a known grate plate (DE-A 24 54 202) which, on the topside, has a heat-resistant and wear-resistant ceramic layer held, with the possibility of horizontal expansion, by the lower part of the plate. The lower part of the plate has fastening elements both in its rear and its front region, from which it is to be concluded that the front region is held and locally fixed by any support parts not disclosed, so that the abovementioned disadvantage cannot arise. In contrast to this, the invention relates to that type, in which the individual grate plate is held solely in its rear region by the grate-plate carrier, projects' freely forwards and contains rib elements which are exposed on top to the effect of the temperature of the material or are fixedly connected to a part exposed to the temperature and which consequently experience the said warping.